A standard felt-tipped fluorescent highlighter is commonly used to accentuate text or other printed images in letters, reports, books, etc. In its brightly colored, semi-translucent state it is effective in drawing one's attention to a particular area of a page. However, this translucency also limits a highlighters' usefulness as it cannot be `seen` by the optics of a photocopier and thereby cannot be consistently reproduced. In addition, facsimile technology cannot distinguish standard highlighter markings and thus cannot transmit the highlighted background.
According to the present invention a method, product, and apparatus are provided for effecting highlighting of text, symbols, or the like in documents so that the highlighting reproduces when the document is reproduced electronically (e.g. by photocopying or by facsimile transmission), while not adversely the text after it has been reproduced. This is effectively provided for according to the present invention--in general--by providing a background tone to the text to be highlighted. A background "tone" is typically produced by screening utilizing dots (the dots may be of any geometric configuration) or lines. It is most desirable according to the invention to utilize a tone produced from dots where the dots are small enough and close enough in proximity to one another to appear as a continuous gray tone. The tone is of sufficient density to effectively highlight the text, but does not impair the legibility of the underlined text/symbols. It is most desirable to provide a tone pattern of about 10-22% density (e.g. approximately 20% density), with about 30-65 lines per inch. Such a tone will adequately highlight the text on documents, while being reproduceable utilizing a photocopier or a facsimile transmission, without the highlighted information being obscured.
According to one aspect of the present invention, an assembly for applying a tone to a document is provided which has many features in common with a conventional marker, being just as portable and as readily usable as a conventional marker. The assembly comprises: An elongated hollow casing having a body portion and a removable cap at one end of the body portion; the one end of the body portion also having a projecting portion, and having means defining an opening in the projecting portion. A rotatable print element having tone applying projections extending radially outwardly from the peripheral surface thereof. Means for mounting the print element for rotation and so that a portion of the peripheral surface thereof extends outwardly from the projecting portion of the casing, through the opening therein. And, a piece of foam mounted in the casing and having a surface thereof in engagement with the print element, and extending from the print element into the casing, for applying ink to the tone applying projections on the print element, so that as the print element is moved along a document, a tone pattern is applied to the document.
Preferably the assembly also comprises surface manifestations formed in the casing body near, but spaced from, the print element to positively position the foam in the casing to fix the length of foam between the surface manifestations and the foam surface engaging a print element. The foam is a parallelipiped, and has notches which cooperate with ridges (providing the surface manifestations) in the preferred embodiment. The surface for engaging the print element is at a first end of the parallelipiped, while the second end engages a liquid reservoir. Preferably from the notch to the first end of the parallelipiped the foam is not significantly compressed (just enough to ensure positive transfer of ink to the print element) but between the notch and the second end the foam may be compressed, without affecting the pressure of the foam on the print element.
The foam is typically a plastic microporous open cell construction, for example having 400-1400 pores per inch. The surface for engaging the print element may have a wide variety of configurations. For example it can be a surface of the foam itself that is flat (and parallel to the axis of rotation of the print element), concave, pointed, slit in a plane containing the axis of rotation, or convex. Alternatively, a plurality of short, parallel, nylon or other fibers can be flocked to one end of the parallelipiped and form the surface (acting as a brush) engaging the print element.
Instead of foam, the element engaging the print element for transferring ink to it may comprise a bundle of capillaries (preferably aligned fibers) which form an ink reservoir, being disposed within a tube of ink impervious material. A short length of fibers may extend outwardly from the tube to engage the print element.
It is preferred that the print element comprise a roller mounted for rotation about a fixed axis, with the tone projections on the circumferential periphery thereof. Alternatively, the print element may comprise a sphere, or it may comprise an endless belt having opposed, in line, interior surfaces thereof and each in engagement with a curved surface operatively attached to the casing body. The curved surface may be a stationary, low friction curved surface, or may comprise a roller mounted about a fixed axis of rotation in the casing body.
The assembly/instrument according to the invention not only can be used for applying tone patterns to documents so as to highlight them for facilitating copying by photocopying machines, and transmission by facsimile machines, they also can be used for shading by artists and draftsmen or may be used as novelty drawing instruments by children. Any type of tone projections can be provided, such as dots of any shape, lines, or other geometric elements.
It is the primary object of the present invention to provide an effective tone pattern applying instrument, having a number of uses, including uses in effecting highlighting of documents so that the highlighted portions will reproduce when the document is electronically copied, but will not obscure the portions they highlight. The disclosed invention also relates to other mechanisms, besides the preferred instrument described above, for accomplishing that same purpose. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.